Fourth generation (4G) cellular networks employing newer radio access technology (RAT) systems that implement the 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) and LTE Advanced (LTE-A) standards are rapidly being developed and deployed within the United States and abroad. LTE-A brings with it the aggregation of multiple component carriers (CCs) to enable this wireless communications standard to meet the bandwidth requirements of multi-carrier systems that cumulatively achieve data rates not possible by predecessor LTE versions.
One mechanism common to LTE and LTE-A, which allows these 4G telecommunication standards to reliably achieve high data rate throughputs is the Hybrid Automatic Repeat Request (Hybrid ARQ or HARQ). LTE HARQ processes are achieved through the collaboration of an LTE base station, i.e., an enhanced NodeB or eNodeB, and a wireless mobile communication device, i.e., a user equipment or UE, at a time when error packets or transmission errors are received by a UE in the downlink (DL), or at a time when error packets or transmission errors are received by an eNodeB in the uplink (UL).
Hybrid ARQ is a combination of high-rate forward error correction (FEC) coding and ARQ error control. In standard ARQ, redundant bits can be added to data to be transmitted to a receiver using an error detecting code such as a cyclic redundancy check (CRC). Receivers detecting a corrupted message can thereby request a new message from the sender. However, in HARQ, transmission data can be encoded with FEC code, where corresponding parity bits are sent with the transmission data. Alternatively, corresponding parity bits may be transmitted at a subsequent time, upon request, when a receiver detects an erroneous transmission.
Further, LTE communications can also employ connected mode discontinuous reception (C-DRX) operations and semi-persistent scheduling (SPS) to allow 4G LTE enabled UEs to conserve local device resources (e.g. battery power, processing power, available memory, etc.) during various radio resource control (RRC) Connected mode operations, such as when a UE is engaged in low bandwidth application data communications, e.g. during periodic voice over LTE (VoLTE) communications. However, the power conservation benefits of C-DRX and SPS operations can be compromised by overlaying HARQ retransmissions thereon, which requires a UE to remain awake for extended periods of time in order for the UE to be able to transmit/receive HARQ acknowledgement (ACK/NACK) messages and then process corresponding DL or UL HARQ retransmissions.
For certain low bandwidth application data communications, such as VoLTE-type data communications, network-designated LTE HARQ timelines can require a UE to remain awake for longer periods of time than necessary. Accordingly, there exists a need for solutions that can conserve local UE device resources by eliminating or reducing various DL and UL HARQ requirements that necessitate a UE remaining active during time periods when the UE could otherwise enter into a C-DRX or an SPS power saving mode.